A Long-Standing Giant Mandibular Ameloblastoma and its Management with Microvascular Free Fibular Graft: a Case Report

Ameloblastoma is one of the most common benign epithelial odontogenic tumors of jaws. We report a case of long-standing slow-growing giant ameloblastoma involving almost all of mandibular bone. The solid multicystic lesion was excised, and the histopathological examination showed the follicular type of ameloblastoma. Furthermore, the defect was reconstructed with microvascular osteocutaneous free fibular graft.


Introduction
Ameloblastoma originates from odontogenic epithelium and it is one of the most common benign odontogenic tumors of the jaw. It may develop from a dental lamina, enamel organ, an odontogenic cyst lining, or basal cells layer of the oral mucosa [1][2]. The cause of the tumoral transformation of oral epithelium is still unknown.
Although ameloblastoma commonly occurs in the molar-ramus area of the mandible, it can arise anywhere in both jaws. Lesions are mostly asympto-matic and found as a painless expansile jaw growth on routine radiographs from the maxillofacial region [1][2]. It usually grows slowly and can reach a gigantic size if left untreated [3]. Neural alteration is uncommon even in large lesions. Radical resection recommended in approaching these benign locally aggressive lesions because of the high recurrence rate when surgical enucleation is performed. Long-standing ameloblastomas or those with repeat recurrence lesion may transform into ameloblastic carcinoma [4]. We report a case of massive ameloblastoma involving the mandible which has been left untreated for 20 years. We also described its management with a free fibular graft. The novelty of the present study was the size, long standing duration of the lesion, and the management of this lesion, which would worth mentioning in the literature.

Case Presentation
The patient was asked to sign an informed consent for the surgical procedure and also to use necessary information for reporting this case. A 63 years-old farmer   proper eating. While previous reports showed higher frequency in male [8], others found that lesion affects young women [9]. The age of the patient in the present study was higher due to patient neglecting the necessary treatment, although patients recall a trauma to face about 30 years ago (in his 30s), which consistent with other reports. The present lesion showed a radiographically intricate multicystic pattern which is considered frequent in the ameloblastic lesion [10]. Similar to the present case, the majority of giant ameloblastomas are highly vascular which is related to their active tumoral proliferation, and may require preceded embolization [11]. Fortunately, our case was managed without embolization. Detection of the lesion is usually accidental and during a radiographic examination of the jaw for another reason. Asymptomatic progression sometimes delays earlier treatment, although some patients experience signs and symptoms such as swelling, pain, altered sensation, dental malocclusion, and facial deformity [12]. has less aggressive behavior [13]. Thus, in our case, it was preferred by the surgeon to wait before reconstruction of the defect. After ensuring no recurrence, the reconstruction was performed.
There is a lack of agreement toward the most appropriate treatment modality between clinicians. Those who advocate conservative treatments such as curettage, enucleation, and cryotherapy presume that these lesions are mostly benign although locally invasive. These conservative approaches have low morbidity than radical modalities such as marginal, segmental, and hemimandibulectomy. Many authors recommend enucleation with periosteal preservation, especially in young children which is essential for bone regeneration [14]. Advocators of radical treatments believe that curettage and enucleation of ameloblastoma lead to a high recurrence rate which has been reported up to 55-90% in the literature [15]. We also believe that radical surgical excision with a margin of 2cm of healthy bone is the best approach in treating these cases.
The bony margin represents a distance from the radiographical margin, which is considered to be diseasefree, and it is oncologically safe to perform osteotomies.
The structural pattern of ameloblastoma in cancellous bone is such that the border of the tumor might lie well beyond the visible macroscopic surface and radiographic boundaries [16]. On account of the large size of the lesion in our case and significant bone defect postoperatively, we have used free fibular flap for mandibular reconstruction ( Figure 5). soft tissue, and if necessary, skin transfer(up to 25cm in length and 5cm in width) with only one donor site. The fibula blood supply is also both intraosseous and segmental, which allows multiple oste-otomies to shape the bone similar to the mandible [15]. Patient and his gaurdians singined a written informed consent for reporting this case.

Conclusion
Microvascular free fibular graft shows a predictable result although it is a technically demanding procedure and experience plays a vital role in reconstructing jaw defects with this method.